1) Field of the Invention
This invention relates generally to the fabrication of dielectric layers for semiconductor devices and more particularly to a method for forming an inter-metal dielectric (IMD) layers using spin-on-glass (SOG) for sub-half-micron semiconductor devices.
2) Description of the Prior Art
Semiconductor elements are continuously being miniaturized in order to make circuits smaller, faster, and less expensive. However this miniaturization creates may challenges. High quality dielectric layers between conductive lines in semiconductor devices is a critical necessity for the submicron feature sized era in the manufacture of integrated circuits. These high quality dielectric layers are required over conductive lines, such as polysilicon gates on the substrate surface (e.g., interlevel dielectric) and such as metal lines over the substrate (e.g. interlevel dielectric). VLSI devices require miniaturization of interconnects, etc., interconnection spaces, resulting in increase in steps formed on the surface of a substrate. This is a particular problem when spacing between conductive lines is less than 0.15 .mu.m.
The manufacturing requirements of intermetal dielectric layers in sub-half micron semiconductor devices include: (1) voidless fill of narrow trenches (gaps) between conductors (metal lines), (2) surface being planar for successful patterning and etching of the new blanket metal deposition, (3) stable with respect to water transport and (4) exhibiting a net compressive stress.
Practitioners have improved planarization methods. For example, U.S. Pat. No. 5,459,105 (Matsumura) describes a planarization method for IMD using PESiO2, O3-TEOS, SOG, etchback and PESiO2. Also, U.S. Pat. No. 5,482,900 (Yang) and U.S. Pat. No. 5,426,076 (Moghadan) show planarization methods. Product literature from Allied Signal Inc, Advance microelectronics materials, 3500 Garrett Drive, Santa Clara Calif. 9554-2827 (phone 408-562-0330), describe Accuspin.RTM. 418 Flowable SOP (X-18), and Accuglass T-11 Series SOG-(111, 211, 211).
However these methods can be further improved to meet the above mentioned requirements and overcome the above mentioned shortcomings.